I've been shooting 2 3/4" shells in all my guns, many of them Damascus barreled SxS's made in the 1800's. At this time have 15 old SxS's, all of them Damascus barreled except three. Over the years I've probably owned over 40 old SxS's. I have always shot 2 3/4" shells in all of them for the past 15 years. Sherman Bell did a test with Tom Amhurst { sp ?] a while back in Double Gun Journal shooting 2 3/4 in 2 1/2" chamber guns. Pressures rose around 500psi. Tom runs a pressure testing facility. Are all 2 1/2 chamber guns safe - no, not with any ammo. But that's like saying all modern guns are safe. They too have blown up. Pressures raise about 500 and that's a fact. Why those guns you looked at blew up - I don't know but seriously doubt it was from firing 2 3/4 shells in them. Would I fire modern 10,500psi loads in my 100+ year old guns ? Not on a regular basis. I have too much respect for 100 year old stocks and don't like to crack them. Another thought that will raise some hackles - Sherman also tried to blow up 20 wall hangers, all Damascus, with Remington proof loads - 18,500psi. Couldn't do it. He and Tom hand loaded up to 31,000psi before one of the barrels on a Parker let go. The other barrel went at 32,000psi. Am I saying all Damascus barrels are safe - no. Just that they're not so unsafe like many would have us believe. Old nitro loads at the turn of the century were quite high, more so than most people think. And, they were shot in Damascus guns. My loads are in the 8000psi or less range, well within what some Damascus and nitro loads were. When Union Metallic Cartridge Co. began offering factory loaded shotgun shells, circa 1891, they offered 10-gauge shells loaded with as much as 5 drams of powder and 1 1/4 ounce of shot. By the 1893 catalog where the SMOKELESS and TRAP shells loaded with smokeless powders were charted separately from the CLUB black powder shells, the heaviest smokeless powder loads offered were 3 3/4 drams pushing 1 1/4 ounces of shot. For 1905, UMC upped the maximum 10-gauge load in their ARROW shell to 4 drams of bulk smokeless powder pushing 1 1/4 ounce of shot. The next year UMC upped the maximum 10-gauge load in their ARROW shell again to 4 1/4 drams of bulk smokeless powder (or 34 grains of dense smokeless powder such as Infallible or Ballistite) pushing 1 1/4 ounce of shot. That remained the heaviest smokeless powder 10-gauge load offered until Western Cartridge Co. introduced their high velocity, progressive burning powder, Super-X Super-Ten load of 1 5/8 ounce of shot in 1926. And, most the old SxS's had chambers a 1/8 shorter than the shell. It was thought that it helped seal the pressure better.